Controller for the Zend Framework - making it testable?

AuthController.php

<?php
/**
 * This holds the auth controller class
 *
 * @package Insight
 * @subpackage Controllers
 */

/**
 * The auth controller class
 *
 * @package Insight
 * @subpackage Controllers
 */
class AuthController extends Zend_Controller_Action
{
    public function indexAction()
    {
        $this->_redirect('/auth/login');
    }

    public function loginAction()
    {
        $view = Zend_Registry::get("view");
        $msg = Zend_Registry::get("message");

        $step = 1;
        if ($this->_request->isPost()) {
            $filters['*'] = 'StringTrim';
            $validators['username'] = new Zend_Validate_Regex('/^[a-zA-Z0-9_-]{1,40}$/');
            $validators['password'] = new Zend_Validate_Regex('/^[a-zA-Z0-9_-]{1,40}$/');
            $validators['smscode'] = new Zend_Validate_Regex('/^[0-9]{4}$/');

            $input = new Zend_Filter_Input($filters, $validators, $_POST);
            if (!$input->isValid('username')) {
                $message = "Ugyldigt brugernavn";
            } elseif (!$input->isValid('password')) {
                $message = "Ugyldigt kodeord";
            } else {
                if ($input->isValid('smscode')) {
                    $smscode = $input->smscode;
                } else {
                    $smscode = null;
                }
                $authada = new Zend_Auth_Adapter_Insight($input->username, $input->password, $_SERVER['REMOTE_ADDR'], $smscode);
                $auth = Zend_Auth::getInstance();
                $result = $auth->authenticate($authada);
                if ($result->isValid()) {
                    $_SESSION['user'] = $result->getIdentity();
                    $this->_redirect('/');
                } else {
                    $authmsg = $result->getMessages();
                    $authmsg = $authmsg[0];
                    if ($authmsg == "user not found") {
                        $message = "Forkert brugernavn eller kodeord";
                    } elseif ($authmsg == "user disabled") {
                        $message = "Brugeren er disabled, kontakt IT på xxxxxxx";
                    } elseif ($authmsg == "ip not allowed, no phone") {
                        $message = "IP ".$_SERVER['REMOTE_ADDR']." ikke tiladt, der kunne ikke findes et telefonnr på brugeren så der kunne ikke sendes en smskode";
                    } elseif ($authmsg == "ip not allowed, smscode sent") {
                        $resdata = $result->getIdentity();
                        $message = "IP ".$_SERVER['REMOTE_ADDR']." ikke tiladt, der er sendt en smskode til telefon: ".$resdata['phone'];
                        $step = 2;
                        $view->assign('username', $input->username);
                        $view->assign('password', $input->password);
                    } elseif ($authmsg == "ip not allowed, wrong smscode") {
                        $message = "Forkert smskode, start venligst forfra";
                        $step = 1;
                    } else {
                        $message = "Kunne ikke foretage login";
                    }
                }
            }
        }
        $view->assign('step', $step);
        if (isset($message)) {
            $view->assign('message', $message);
        }
        echo $view->render("auth/login.tpl");
    }

    public function logoutAction()
    {
        $auth = Zend_Auth::getInstance()->clearIdentity();
        $this->_redirect('/auth/login');
    }
}